Are Drums Interchangeable When Replacing Hydraulic Brakes With Electric Brakes

Question:

Currently I have the 9-44 drums on my trailer. When I searched for 10k drums all I got was the 9-27. If I have 9-44 drums can I replace them with 9-27 drums? Also I want to go with electric brakes because I currently have hydraulic brakes but all the components need replaced including the electric over hydraulic actuator and it woud be much cheaper to convert to electric. My truck can stop the trailer and I have been hauling for a while now with zero trailer brakes at all so I think electric would be ok for me. Can I use electric brakes with my current 9-44 drums and with the 9-27 drums. My concern is the holes through the drums do not provide a smooth surface for the magnet to slip over. Or does the magnet slide more toward the outside of the drum thus avoiding the holes? thank you

asked by: Marvin

Expert Reply:

I have attached a link to a helpful article that explains all of the components needed for adding electric drum brakes to a trailer. We always recommend replacing all of the components at one time so you are sure everything works well. If you check out your 9-44 drum you currently have and the inside surface shows no signs of wear or damage you can use them when changing from hydraulic to electric brakes.

I spoke with my contact at Dexter and they told me that all you would have to replace is the brakes on your system and not replace the drums. The drums are different, as the 9-44 drum measures 12-1/4 by 3-3/8, and the 9-27 drum measures 12-1/4 by 4. They are not interchangeable.

They told me that for you to convert to Electric brakes, you would need part # 23-450 for the left hand, and part # 23-451 for the right hand side. This would work fine with your 9-44 drums you currently have.

There are a few things to look at to determine which brake assemblies will fit your trailer. First, look at the bolt pattern of the brake mounting flange. The brake mounting flange is a plate that is welded at the base of the spindle with bolt holes in it. Most brake mounting flanges on 10,000 lb axles have 7 bolt holes, but there are some axles with a 5 bolt pattern.

The next factor to consider is the size of the brake assemblies themselves. If you have your old brakes, measure the overall diameter and the width of the brakes (or width of the brake shoes). You can also measure the diameter of your hubs and the width of the inside of the hub where the brake assembly fits. Most brake assemblies for 10,000 lb axles are 12-1/4 inches x 3-3/8 inches or 12-1/4 inches x 4 inches.

To find the right drum you will need to know a couple of things to make sure you select the correct hub and drum that is compatible with your trailer spindles. The stamped numbers on the bearings and seals will help and also the wheel bolt pattern of the existing hubs. If you cannot find the part numbers on the bearing and seals you can measure the spindles at the inner and outer bearing surfaces using a precision instrument like a dial caliper. I have included a drawing that shows where the measurements need to be taken on the spindle.

When current is sent to the magnet, it moves just a very small amount toward the inside surface of the drum allowing the brake pads to engage the inside surface of the drum. You should have no problem with the magnet sliding over any of the holes.

I have included a link to our product page for electric brake assemblies for 10000 lb axles.